The AIDS (acquired immunodeficiency syndrome) epidemic has transformed and raised the risks associated with substance abuse. Because of their day-to-day contact with alcohol and drug abusers, substance abuse agencies will increasingly meet with demands to incorporate interventions designed to prevent HIV (human immunodeficiency virus) infection among alcohol and drug abusers and their sexual partners. We propose to conduct and evaluate a safer sex intervention at a substance abuse agency with high rates of high-risk sex for HIV transmission among their clients. The model that we will evaluate has been designed to meet several important criteria: 1) it is consistent with AIDS prevention theory, while specifically addressing the needs of recovering alcoholics/drug addicts, 2) it does not contradict the goals of substance abuse treatment, 3) it is culturally relevant to the study population, and 4) it can be easily incorporated into other agencies' substance abuse treatment programs without requiring extensive staff training or large investments in training materials. Data from this project will be used to describe levels of sexual risk at a substance use treatment agency, both before and after the intervention. Secondly, we will evaluate the effects of the intervention on levels of sexual risk and substance abuse treatment recidivism as manifested within a treatment and control group. Finally, we will determine the psychosocial determinants of treatment success and failure in order to understand how risk for HIV transmission can be further lowered within a clinical substance-abusing population. These goals will prove central to the final development and dissemination of this prevention model.